JP3199083B2 - Automatic tracking control method and magnetic recording / reproducing apparatus using this method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention is particularly useful for EP regeneration.
The present invention relates to an automatic tracking control method capable of obtaining a reproduced image with the best image quality, and a magnetic recording / reproducing apparatus using the method.

[0002]

2. Description of the Related Art FIG. 3 is a block circuit diagram of an automatic tracking control system of a conventional magnetic recording / reproducing apparatus, wherein 1 is a rotary drum, 2 and 3 are rotary heads mounted on the rotary drum 1, Scans a recording track recorded on the magnetic tape 4 to pick up a reproduction signal. Reference numeral 5 denotes a head amplifier circuit which amplifies a reproduction signal picked up by the rotary heads 2 and 3. Reference numeral 6 denotes a detection circuit which detects the amplified reproduction signal and converts it into a DC voltage. Reference numeral 7 denotes an A / D conversion circuit which converts the DC voltage into a digital signal and inputs the digital signal to the microcomputer 8. Reference numeral 9 denotes a servo circuit which drives the capstan motor 11 through the capstan drive circuit 10 and the drum motor drive circuit 1
The drum motor 13 through 2, and controls so that each becomes a predetermined speed and phase, microcontroller Manipulator over data 8
, A so-called tracking adjustment for automatically adjusting the phase of the rotary drum 1 based on the control pulse picked up by the control head 14 and the output of the PG head 15 is automatically performed.

Next, the operation of this conventional example will be described with reference to the flowchart of FIG. Microcontroller Publicis over data 8,
Upon receiving the command for the reproducing operation, the reproducing operation is started in S1,
In S2, a predetermined tracking phase value is designated for the servo circuit 9, and in S3, the reproduced signal picked up by the rotary heads 2 and 3 and input through the head amplifier 5, the detection circuit 6, and the A / D conversion circuit 7 is input. the level is stored in the memory of the micro <br/> con Manipulator over data 8.

[0004] Next, microcontroller Publicis over data 8, S4
Specifies the tracking phase value shifted by a predetermined amount from the initially specified tracking phase value to the servo circuit 9. After the servo system is stabilized in S5, the level of the reproduction signal corresponding to the tracking phase value is set to micro level. Con pin
It is stored in the memory of the-menu data 8. Next, the operations of S4 and S5 are repeated until the range of the tracking phase value specified in S6 covers the entire range of the predetermined fixed tracking range from point A to point B shown in FIG.

Next, in step S7, a maximum or near tracking phase value (point C) of the level of the reproduction signal stored in the memory is detected, and in step S8, the detected tracking phase value is set as a reference value and the servo circuit is used. 9 and then enters the monitoring mode at S9, where the level E of the reproduced signal is
When the tracking error is lower than the level D at the point C determined by 8 and exceeds a predetermined tracking error allowable amount α, the process returns to S4 to restart the operation of resetting the tracking phase value.

FIG. 5 is a characteristic diagram showing the relationship between the level of the reproduction signal and the tracking phase value during EP reproduction. During normal reproduction, the level of the reproduction signal having a single-peak characteristic becomes trapezoidal, and the maximum value cannot be detected. Therefore, at the time of EP reproduction, in step S7, the AC:
The tracking phase value at the point C where the BC ratio is 2: 6 in the VHS recording tape and 3: 5 in the S-VHS recording is calculated and given to the servo circuit as a reference value.

However, in the case of the EP reproduction, the positions of the points A and B become unstable due to a crosstalk component and the like, and accordingly, the position of the point C calculated also fluctuates.

[0008]

The conventional automatic tracking adjustment system is configured as described above.
During EP playback, the level of the playback signal fluctuates due to crosstalk components and the like, so that the tracking phase value given as a reference value fluctuates, and the tracking phase is not fixed to the best point of the image quality. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has an automatic tracking adjustment that can perform automatic tracking adjustment so that the quality of a reproduced video image is optimized even during SP reproduction and EP reproduction. It is an object to obtain a tracking control method and a magnetic recording / reproducing apparatus using the tracking control method.

[0010]

An automatic tracking control method according to the present invention detects a tracking phase value at which a sum of a noise level of a horizontal synchronizing signal of a reproduced video signal and a level of a crosstalk component of a chroma signal is minimized. Then, the reference value is given to the tracking servo system.

Further, the magnetic recording / reproducing apparatus according to the present invention includes means for detecting the noise level of the horizontal synchronizing signal of the reproduced signal and the level of the crosstalk component of the chroma signal, and the sum of the levels of the two signals is minimized. Means for providing the tracking phase value to the tracking servo system as a reference value.

[0012]

According to the present invention, the tracking is automatically adjusted so that the sum of the noise level of the horizontal synchronizing signal of the video signal and the level of the crosstalk component of the chroma signal is minimized. The tracking phase can be fixed at the best point of the image quality of the video signal.

[0013]

[Embodiment 1] FIG. 1 is a block circuit diagram of an automatic tracking control system of a magnetic recording / reproducing apparatus according to a first embodiment of the present invention. In FIG. 1, reference numeral 17 denotes an FM demodulator for converting a reproduction signal from an FM signal to a video signal, 18 a synchronization separation circuit for separating a horizontal synchronization signal from a video signal, 19 an amplifier, and 20 an envelope detection circuit which is amplified by an amplifier 19. The horizontal synchronization signal thus obtained is subjected to envelope detection, and is converted into a DC voltage that changes depending on the level of noise in the horizontal synchronization signal portion. Reference numeral 21 denotes a chroma circuit for obtaining a chroma signal by performing processing such as frequency conversion on a low-frequency reproduction signal input from the head amplifier 5; 22, a 1H delay unit; 23, a subtractor; in the detection circuit for detecting crosstalk components of Rukuro Ma signal, the output signal of the envelope detector circuit 20 and detector circuit 24 are respectively at a-D converter circuit 7 is converted into digital data, in the memory of the Microcon repeater 8 It is memorized.

Next, the operation of the first embodiment will be described with reference to the flowchart of FIG. Microcontroller Publicis over data 8
Receives a reproduction operation command, starts a reproduction operation in S10, and then specifies a predetermined tracking phase value to the servo circuit 9 in S11. At this time, the reproduced signals picked up by the rotary heads 2 and 3 are passed through the head amplifier 5, FM demodulator 17, synchronization separation circuit 18 and amplifier 19, and the horizontal synchronization signal of the video signal is input to the envelope detection circuit 20 and The voltage is converted to a voltage and input to the AD conversion circuit 7.

On the other hand, the head amplifier 5 and the chroma circuit 2
The chroma signal reproduced through 1 is output from the 1H delay unit 22 to 1
The signal is delayed by H and subtracted from the chroma signal after 1H by the subtractor 23 to become a crosstalk component from which the normal chroma signal has been removed. The crosstalk component is detected by the detection circuit 24 and converted into a DC voltage. Is entered. AD conversion circuit 7
Converts the input signals respectively to the digital data input to the microcontroller Manipulator over data 8 is stored into the memory at S12.

Next, the microcomputer 8 operates in S13.
In the servo circuit 9, to specify the tracking phase value by a predetermined amount shifted from the first tracking phase value, S
Servo system stores the level of the crosstalk component of the horizontal synchronizing signal level and black Ma signal to the memory corresponding to the tracking phase value After stable at 14. Next, S1
The operations of S13 and S14 are repeated until the range of the tracking phase value specified in 5 reaches the entire tracking fixed range from point A to point B shown in FIG.

Next, at step S16, a tracking phase value at which the sum A of the horizontal synchronizing signal noise level and the chroma signal crosstalk component level at each tracking phase value stored in the memory is minimized is detected. The detected tracking phase value is supplied to the servo circuit 9 as a reference value, and then enters the monitoring mode in S18. If it exceeds the tracking error allowable value α from the sum A, the process returns to S13 to restart the reference value resetting operation.

As described above, according to the first embodiment, since an appropriate tracking phase value is always given as the reference value of the tracking servo system, the reproduced image of the best image quality can be obtained not only during SP reproduction but also during EP reproduction. , And a great effect can be obtained particularly during EP reproduction.

[0019]

As described above, according to the present invention, the tracking adjustment is automatically performed so that the sum of the noise level of the horizontal synchronizing signal and the level of the crosstalk component of the chroma signal is minimized. Thus, there is an effect that a reproduced image having the image quality of

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of an automatic tracking control system of a magnetic recording / reproducing apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a flowchart of the first embodiment.

FIG. 3 is a block circuit diagram of an automatic tracking control system of a conventional magnetic recording / reproducing apparatus.

FIG. 4 is a flowchart of a conventional example.

FIG. 5 is a characteristic diagram showing a relationship between a level of a reproduction signal and a tracking phase value.

[Explanation of symbols]

7 A-D converter circuit 8 microcontroller Manipulator over data 9 servo circuit 12 the drum motor drive circuit 17 FM demodulator 18 sync separator 20 envelope detector circuit 21 chroma circuit 22 IH delayer 23 subtractor

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04N 5/782-5/783 H04N 9/79-9/898 G11B 15/467

Claims (2)

(57) [Claims] A tracking phase value shifted by a predetermined value within a predetermined tracking fixed range is given to a tracking servo system as a reference value, and a noise level of a horizontal synchronizing signal of a reproduction signal and a chroma signal of a tracking signal at each tracking phase value are provided. An automatic tracking control method that detects a tracking phase value at which the sum of the levels of the crosstalk components is minimized, and controls the tracking servo system using the detected tracking phase value as a reference value. 2. A plurality of tracking phase values shifted by a predetermined value within a predetermined tracking fixed range are sequentially given to a tracking servo system as reference values, and are included in a horizontal synchronizing signal of a reproduction signal at each tracking phase value. Means for detecting the noise level and the level of the crosstalk component of the chroma signal, means for detecting the tracking phase value at which the sum of the noise level and the level of the crosstalk component at each tracking phase value is minimum, and Means for providing a tracking phase value to the tracking servo system as a reference value.